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Return angles as array, add requirements and examples to doc

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Zach Kozar 2023-05-05 00:00:25 -04:00
parent 889cf2f71d
commit 033f722d4f
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1 changed files with 87 additions and 24 deletions
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111
src/geometry/rotation_specialization.rs
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@ -983,7 +983,64 @@ impl<T: SimdRealField> Rotation3<T> {
/// Represent this rotation as Euler angles.
///
/// Returns the angles produced in the order provided by seq parameter, along with the
/// observability flag. If the rotation is gimbal locked, then the observability flag is false.
/// observability flag. The Euler axes passed to seq must form an orthonormal basis. If the
/// rotation is gimbal locked, then the observability flag is false.
///
/// # Panics
///
/// Panics if the Euler axes in `seq` are not orthonormal.
///
/// # Example 1:
/// ```
/// use std::f64::consts::PI;
/// use approx::assert_relative_eq;
/// use nalgebra::{Matrix3, Rotation3, Unit, Vector3};
///
/// // 3-1-2
/// let n = [
/// Unit::new_unchecked(Vector3::new(0.0, 0.0, 1.0)),
/// Unit::new_unchecked(Vector3::new(1.0, 0.0, 0.0)),
/// Unit::new_unchecked(Vector3::new(0.0, 1.0, 0.0)),
/// ];
///
/// let r1 = Rotation3::from_axis_angle(&n[2], 20.0 * PI / 180.0);
/// let r2 = Rotation3::from_axis_angle(&n[1], 30.0 * PI / 180.0);
/// let r3 = Rotation3::from_axis_angle(&n[0], 45.0 * PI / 180.0);
///
/// let d = r3 * r2 * r1;
///
/// let (angles, observable) = d.euler_angles_ordered(n, false);
/// assert!(observable);
/// assert_relative_eq!(angles[0] * 180.0 / PI, 45.0, epsilon = 1e-12);
/// assert_relative_eq!(angles[1] * 180.0 / PI, 30.0, epsilon = 1e-12);
/// assert_relative_eq!(angles[2] * 180.0 / PI, 20.0, epsilon = 1e-12);
/// ```
///
/// # Example 2:
/// ```
/// use std::f64::consts::PI;
/// use approx::assert_relative_eq;
/// use nalgebra::{Matrix3, Rotation3, Unit, Vector3};
///
/// let sqrt_2 = 2.0_f64.sqrt();
/// let n = [
/// Unit::new_unchecked(Vector3::new(1.0 / sqrt_2, 1.0 / sqrt_2, 0.0)),
/// Unit::new_unchecked(Vector3::new(1.0 / sqrt_2, -1.0 / sqrt_2, 0.0)),
/// Unit::new_unchecked(Vector3::new(0.0, 0.0, 1.0)),
/// ];
///
/// let r1 = Rotation3::from_axis_angle(&n[2], 20.0 * PI / 180.0);
/// let r2 = Rotation3::from_axis_angle(&n[1], 30.0 * PI / 180.0);
/// let r3 = Rotation3::from_axis_angle(&n[0], 45.0 * PI / 180.0);
///
/// let d = r3 * r2 * r1;
///
/// let (angles, observable) = d.euler_angles_ordered(n, false);
/// assert!(observable);
/// assert_relative_eq!(angles[0] * 180.0 / PI, 45.0, epsilon = 1e-12);
/// assert_relative_eq!(angles[1] * 180.0 / PI, 30.0, epsilon = 1e-12);
/// assert_relative_eq!(angles[2] * 180.0 / PI, 20.0, epsilon = 1e-12);
/// ```
///
/// Algorithm based on:
/// Malcolm D. Shuster, F. Landis Markley, “General formula for extraction the Euler
@ -994,11 +1051,11 @@ impl<T: SimdRealField> Rotation3<T> {
&self,
mut seq: [Unit<Vector3<T>>; 3],
extrinsic: bool,
) -> (Vector3<T>, bool)
) -> ([T; 3], bool)
where
T: RealField + Copy,
{
let mut angles = Vector3::zeros();
let mut angles = [T::zero(); 3];
let eps = T::from_subset(&1e-7);
let _2 = T::from_subset(&2.0);
@ -1007,6 +1064,8 @@ impl<T: SimdRealField> Rotation3<T> {
}
let [n1, n2, n3] = &seq;
assert_relative_eq!(n1.dot(n2), T::zero(), epsilon = eps);
assert_relative_eq!(n3.dot(n1), T::zero(), epsilon = eps);
let n1_c_n2 = n1.cross(n2);
let s1 = n1_c_n2.dot(n3);
@ -1020,53 +1079,59 @@ impl<T: SimdRealField> Rotation3<T> {
c.transpose_mut();
let r1l = Matrix3::new(
T::one(), T::zero(), T::zero(),
T::zero(), c1, s1,
T::zero(), -s1, c1,
T::one(),
T::zero(),
T::zero(),
T::zero(),
c1,
s1,
T::zero(),
-s1,
c1,
);
let o_t = &c * self.matrix() * (c.transpose() * r1l);
angles.y = o_t.m33.acos();
angles[1] = o_t.m33.acos();
let safe1 = angles.y.abs() >= eps;
let safe2 = (angles.y - T::pi()).abs() >= eps;
let safe1 = angles[1].abs() >= eps;
let safe2 = (angles[1] - T::pi()).abs() >= eps;
let observable = safe1 && safe2;
angles.y += lambda;
angles[1] += lambda;
if observable {
angles.x = o_t.m13.atan2(-o_t.m23);
angles.z = o_t.m31.atan2(o_t.m32);
angles[0] = o_t.m13.atan2(-o_t.m23);
angles[2] = o_t.m31.atan2(o_t.m32);
} else {
// gimbal lock detected
if extrinsic {
// angle1 is initialized to zero
if !safe1 {
angles.z = (o_t.m12 - o_t.m21).atan2(o_t.m11 + o_t.m22);
angles[2] = (o_t.m12 - o_t.m21).atan2(o_t.m11 + o_t.m22);
} else {
angles.z = -(o_t.m12 + o_t.m21).atan2(o_t.m11 - o_t.m22);
angles[2] = -(o_t.m12 + o_t.m21).atan2(o_t.m11 - o_t.m22);
};
} else {
// angle3 is initialized to zero
if !safe1 {
angles.x = (o_t.m12 - o_t.m21).atan2(o_t.m11 + o_t.m22);
angles[0] = (o_t.m12 - o_t.m21).atan2(o_t.m11 + o_t.m22);
} else {
angles.x = (o_t.m12 + o_t.m21).atan2(o_t.m11 - o_t.m22);
angles[0] = (o_t.m12 + o_t.m21).atan2(o_t.m11 - o_t.m22);
};
};
};
let adjust = if seq[0] == seq[2] {
// lambda = 0, so ensure angle2 -> [0, pi]
angles.y < T::zero() || angles.y > T::pi()
angles[1] < T::zero() || angles[1] > T::pi()
} else {
// lamda = + or - pi/2, so ensure angle2 -> [-pi/2, pi/2]
angles.y < -T::frac_pi_2() || angles.y > T::frac_pi_2()
angles[1] < -T::frac_pi_2() || angles[1] > T::frac_pi_2()
};
// dont adjust gimbal locked rotation
if adjust && observable {
angles.x += T::pi();
angles.y = _2 * lambda - angles.y;
angles.z -= T::pi();
angles[0] += T::pi();
angles[1] = _2 * lambda - angles[1];
angles[2] -= T::pi();
}
// ensure all angles are within [-pi, pi]
@ -1079,9 +1144,7 @@ impl<T: SimdRealField> Rotation3<T> {
}
if extrinsic {
let tmp = angles.x;
angles.x = angles.z;
angles.z = tmp;
angles.reverse();
}
(angles, observable)